Pollution monitors in the Baltimore area have found what many people long suspected: The air we're breathing is bad for us.

Four air sampling stations set up last year by the Maryland Department of the Environment have detected an invisible "soup" of nearly 40 toxic chemicals blanketing the city and Dundalk in southeast Baltimore County that includes high levels of cancer-causing compounds linked mainly to car exhaust and gasoline vapors.

The samples were collected for 24 hours every six days.

Air sampled near downtown, for instance, contained concentrations of benzene that were nearly five times the limit set by state pollution regulations to protect the public.

Levels of another chemical -- 1,3-butadiene -- were 20 times what would be allowed under the state's toxic air pollution regulations.

"We have some problems that are out there," acknowledged George Ferreri, MDE's director of air management.

Maryland environmental officials say the sampling shows that motor vehicles, instead of industrial plants, are the major source of cancer-causing air pollution in Baltimore, as in other cities.

Spokesmen for the chemical industry, which is fighting proposed new city zoning restrictions, called a press conference yesterday to say the state air sampling results prove that southern Baltimore residents have more to fear from auto pollution than from the chemical plants in their midst.

"The chemical industry is not a major source -- in fact it is a very minor source -- of cancer-causing chemicals," said Louis H. Kistner, president of the Chemical Industry Council of Maryland.

The state's air monitors measured higher levels of airborne carcinogenic chemicals at Oldtown fire station near downtown than at two sampling stations in South Baltimore -- one near FMC Corp.'s pesticide plant and another in Fairfield, near three other chemical plants.

Residents of Brooklyn and Curtis Bay have complained about air pollution, chemical spills, odors and dust from heavy industry, landfills and incinerators near their homes.

Prompted by those complaints, the city council now is considering two bills that would require council approval of any new chemical plant or expansion of an existing facility that releases toxic air pollution. The legislation also would set up a "buffer strip" between industry and residential neighborhoods.

Industry officials have complained that the bills will lower land values and don't protect the public.

Kistner contended that the chemical industry is responsible for less than 1 percent of the cancer risk from air pollution in South Baltimore, based on the state's air sampling and on the companies' own estimates of their toxic emissions.

State environmental officials said they had not studied the issue themselves, but they did not dispute Kistner's claim.

The U.S. Environmental Protection Agency estimates that the urban "soup" of toxic air pollution causes between 1,700 and 2,700 cancer cases a year nationwide. The EPA has said motor vehicles are responsible for 56 percent of the cancer-causing pollution in this country, while industry contributes 25 percent.

Maryland industries already have moved to cut their emissions of cancer-causing and highly toxic chemicals by more than 80 percent since the state's toxic air pollution regulations took effect last July, according to George "Tad" Aburn, MDE's chief of air toxics control.

In heavily industrialized South Baltimore, such emissions are being cut back by 95 percent by next year, largely as the result of consent agreements that the state negotiated with chemical plants and other factories in the area.

Vista Chemical Co., for instance, has agreed to reduce its airborne emissions of benzene 75 percent, from 29,000 pounds per year to 7,000 pounds annually by the end of this year, Aburn said.

But benzene, which was detected at excessive levels in all four sampling stations, also is an ingredient of gasoline. Butadiene, likewise found at harmful concentrations everywhere, is produced mainly by car and truck exhaust.

Community leaders and environmental activists, who have fought a losing battle the past two years against a medical waste incinerator in Hawkins Point, said they were skeptical of the chemical industry's claim that air quality is relatively good in South Baltimore.

"All these people from the chemical companies who say how great it is here, you ask them where they live," said Gloria Sipes, the Community Association of Curtis Bay.

"There are still very serious air quality problems that are not being addressed," said Mary Rosso, president of the Maryland Waste Coalition, noting that residents must endure accidental chemical leaks and spills and that some suffer from respiratory ,, problems aggravated by air pollution.